Howard Marks, an Oxford-educated drug trafficker who at his peak in the 1970s controlled a substantial fraction of the world’s hashish and marijuana trade, and who became a best-selling author after his release from an American prison, died on Sunday. He was 70.

His death, from colorectal cancer, which he disclosed last year, was confirmed by Robin Harvie, publisher for nonfiction at Pan Macmillan, which released Mr. Marks’s final book, “Mr. Smiley: My Last Pill and Testament,” in September. No other details were provided.

Mr. Marks’s drug-smuggling career started at Oxford University, where he studied physics and philosophy in the 1960s and peddled marijuana on the side. (He swore off harder substances, like heroin and cocaine, after his friend Joshua Macmillan, a grandson of the former British prime minister Harold Macmillan, died of an overdose.)

In a 1996 autobiography, “Mr. Nice” — Donald Nice was one of his aliases — Mr. Marks wrote that his induction into the drug trade followed a chance encounter with a Pakistani supplier.

He eventually teamed up with James McCann, an Irish Republican Army operative, who arranged for large shipments of hashish through Ireland. Mr. Marks and his accomplices then laundered the proceeds through a staggering array of front companies. They widened their activities to include the United States and Canada in 1973.

Mr. Marks was arrested on drug charges in Nevada in 1976, but he failed to appear in court and fled. His elusiveness made him something of a legend; in 1979, he appeared on a stage in London, flanked by Elvis Presley impersonators, only to disappear again. He was eventually arrested in the Scottish Highlands, where he had imported 15 tons of marijuana from Colombia with a street value of $30 million. In 1980 he faced narcotics charges in London.

To the government’s embarrassment, he was acquitted at his trial after arguing that he had been an agent of MI6, the British equivalent of the C.I.A. In fact, his relationship with the agency had ended years earlier.

“That was intimidating, to see that he had defeated the system, that he had somewhat created an aura about him that he was untouchable,” Craig Lovato, a Drug Enforcement Administration agent who helped bring down Mr. Marks, told the PBS series “Frontline.”

Mr. Marks with a copy of his autobiography.CreditUrsula Dueren/European Pressphoto Agency

It was the United States that eventually brought him to justice. In July 1988, Mr. Marks and his wife, the former Judith Lane, were arrested on the Spanish island of Majorca and charged with 20 accomplices.

They were accused of involvement in a drug-smuggling ring that encompassed — along with Britain, Canada and the United States — Australia, Hong Kong, the Netherlands, Pakistan, the Philippines, Portugal, Singapore, Spain, Thailand and West Germany.

The authorities seized more than $9 million in cash from the group, in addition to properties including a 103-foot-long boat in Vancouver, British Columbia.

“Mr. Marks was the Marco Polo of the drug traffic,” Thomas V. Cash, the special agent in charge of the Miami division of the D.E.A., said at the time. “He perfected smuggling methods and intricate laundering operations involving many countries around the globe, and this is why it took efforts in so many countries to complete this case.”

According to the indictment, Mr. Marks’s network smuggled “thousands of tons” of marijuana and hashish into the United States and Canada from 1973 to 1988. Sentenced to 25 years in prison in 1990, Mr. Marks was held in a high-security federal penitentiary in Terre Haute, Ind. He was released in 1995.

Returning to Britain, Mr. Marks capitalized on his notoriety. His autobiography was the first of several books he published, including a novel. The autobiography was the basis for a film, also called “Mr. Nice,” which was released in the United States in June 2011.

In his review of the movie in The New York Times, Stephen Holden wrote, “Those of us who were old enough in the 1960s and early ’70s to recall the smug, superior attitude (tinged with paranoia) of the period’s hipoisie will recognize his type and wonder exactly what happened to all those Mr. Tambourine Men preaching drugs, sex and rock ‘n’ roll.”

Mr. Marks also ran for Parliament, unsuccessfully, in 1997 on a single-issue platform of cannabis legalization.

Dennis Howard Marks was born on Aug. 13, 1945, in Kenfig Hill, a village in southern Wales. He was twice divorced; his second wife, Judy Marks, wrote her own memoir, “Mr. Nice and Mrs. Marks: Life With Howard,” published in 2006.

He is survived by their three children — Amber, Francesca and Patrick — as well as a daughter, Myfanwy, from a previous marriage.

A version of this article appears in print on , on Page B8 of the New York edition with the headline: Howard Marks, Drug Smuggler Turned Author, 70. Order Reprints | Today’s Paper | Subscribe